U.S. patent number 4,300,562 [Application Number 06/120,195] was granted by the patent office on 1981-11-17 for laminated structures having gathered marginal portions.
This patent grant is currently assigned to Johnson & Johnson Baby Products Company. Invention is credited to Heinz A. Pieniak.
United States Patent |
4,300,562 |
Pieniak |
November 17, 1981 |
Laminated structures having gathered marginal portions
Abstract
A laminated structure having a gathered marginal area which
provides an improved fit about a portion of the human body, said
laminated structure comprising an elastic member disposed between
first and second substrates of flexible gatherable material, said
elastic member comprising a plurality of interconnected
longitudinally extending elastic elements defining apertures
therebetween, the longitudinally extending elements having
different cross-sectional areas to provide varying degrees of
tension across the width of the marginal area and the first and
second substrates of said laminated structure being secured
together through at least some of said apertures.
Inventors: |
Pieniak; Heinz A. (Chicago,
IL) |
Assignee: |
Johnson & Johnson Baby Products
Company (New Brunswick, NJ)
|
Family
ID: |
22388807 |
Appl.
No.: |
06/120,195 |
Filed: |
February 11, 1980 |
Current U.S.
Class: |
604/385.26;
2/237; 428/194; 604/373; 2/401; 604/370; 604/389 |
Current CPC
Class: |
A41F
9/02 (20130101); A61F 13/49017 (20130101); A61F
13/4902 (20130101); B32B 3/26 (20130101); B32B
7/05 (20190101); B32B 5/26 (20130101); B32B
2555/02 (20130101); Y10T 428/24793 (20150115) |
Current International
Class: |
A41F
9/00 (20060101); A61F 13/15 (20060101); A41F
9/02 (20060101); B32B 5/26 (20060101); B32B
5/22 (20060101); A41B 013/02 (); A41B 007/00 () |
Field of
Search: |
;128/284,286,287,288
;2/76,78C,123,221,401,237,DIG.7 ;428/12,61,167,194,231,247 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosenbaum; C. Fred
Attorney, Agent or Firm: Minier; Robert L. Michaels; Martha
A.
Claims
I claim:
1. A laminated structure having a gathered marginal area to provide
improved fit about a portion of the human body comprising: first
and second layers positioned adjacent to one another, said layers
being formed of flexible gatherable material, an elastic member
disposed between said layers in the marginal area thereof, said
elastic member comprising a plurality of interconnected
longitudinally extending elastic elements defining apertures
therebetween, said elements having different cross sectional areas
to provide varying degrees of tension across the width of said
marginal area, said first and second layers being secured together
through at least some of said apertures.
2. A laminated structure as in claim 1 wherein the first and second
layers in the marginal area comprise a single piece of folded
material.
3. A laminated structure as in claim 1 wherein the longitudinally
extending elastic element adjacent the outermost edge of the
marginal area has the greatest degree of tension.
4. A laminated structure as in claim 3 wherein the degree of
tension substantially uniformly decreases across the width of the
marginal area.
5. A disposable diaper comprising: a moisture-permeable facing
layer, an absorbent panel at one side of said facing layer, said
absorbent panel being smaller than said facing layer so that
marginal portions of the facing layer extend outwardly beyond the
edges of said absorbent panel; a moisture-impervious backing layer
at the side of said absorbent panel opposite said facing layer,
said backing layer being larger than said absorbent panel so that
marginal portions of the backing layer extend outwardly beyond the
edges of said absorbent panel; means bonding said facing and
backing layers to one another; and an elastic member disposed in at
least one marginal portion, and affixed therein, said elastic
member comprising a plurality of interconnected longitudinally
extending elastic elements defining apertures therebetween, said
elements having differential cross-sectional areas to provide
varying degrees of tension across the width of said marginal
portions.
6. A disposable diaper as in claim 5 wherein said elastic member is
disposed between said facing layer and said backing layer.
7. A disposable diaper as in claim 6 wherein said facing layer and
said backing layer are secured to each other between the
longitudinally extending elastic elements of said elastic
members.
8. A disposable diaper as in claim 5 wherein the longitudinally
extending elastic element adjacent the outermost edge of said
marginal portion has the greatest degree of tension.
9. A disposable diaper as in claim 8 wherein the degree of tension
substantially uniformly decreases across the width of the marginal
portion.
10. A disposable diaper comprising: a moisture-permeable facing
layer; an absorbent panel at one side of said facing layer, said
absorbent panel being smaller than said facing layer so that side
marginal portions of the facing layer extend outwardly beyond the
side edges of said absorbent panel; a moisture-impervious backing
layer at the side of said absorbent panel opposite said facing
layer, said backing layer being larger than said absorbent panel so
that side marginal portions of the backing layer extend outwardly
beyond the side edges of said absorbent panel; means bonding said
facing and backing layers to one another; and an elastic member
disposed in each of said side marginal portions, and affixed
therein, said elastic members comprising a plurality of
interconnected longitudinally extending elastic elements defining
apertures therebetween, said elements having different
cross-sectional areas to provide varying degrees of tension across
the width of said marginal portions.
11. A disposable diaper as in claim 10 wherein the longitudinally
extending elastic elements adjacent the outermost edge of each side
marginal portion have the greatest degree of tension.
12. A disposable diaper as in claim 11 wherein the degree of
tension substantially uniformly decreases across the width of each
side marginal portion.
13. A disposable diaper as in claim 12 wherein said elastic members
are disposed between said facing layer and said backing layer.
14. A disposable diaper as in clain 13 wherein said facing and
backing layers are secured to each other through at least some of
said apertures.
15. A disposable diaper comprising: a first outer layer in the form
of a moisture-impervious backing; an absorbent panel positioned in
superposed relationship with respect to said backing, said panel
being smaller than said backing and spaced inwardly from the sides
and ends thereof; a second outer layer in the form of a
moisture-pervious facing positioned in superposed relationship with
respect to said panel, said facing being larger than said panel and
having side and end marginal portions thereof secured to said
backing; an elastic member disposed in each side margin of the
diaper, and affixed therein, said elastic member comprising a
plurality of interconnected longitudinally extending gathering
elements defining apertures therebetween, said elements having
different cross-sectional areas to provide varying degrees of
tension across the width of said side marginal portions.
16. A disposable diaper as in claim 15 including a gathering means
disposed in at least one end margin of the diaper.
17. A disposable diaper as in claim 16 wherein the longitudinally
extending elastic elements adjacent the outermost edge of each side
marginal portion have the greatest degree of tension.
18. A disposable diaper as in claim 17 wherein the degree of
tension substantially uniformly decreases across the width of each
side marginal portion.
19. A disposable diaper as in claim 18 wherein said elastic members
are disposed between said facing and said backing layer.
20. A disposable diaper as in claim 19 wherein said facing and
backing layers are secured to each other through at least some of
said apertures.
21. A disposable diaper as in claim 20 including a gathering means
disposed in at least one end margin of the diaper.
22. A disposable diaper as in claim 21 wherein said gathering means
comprises a plurality of interconnected gathering elements defining
apertures therebetween.
23. A disposable undergarment, suitable for use in training infants
or by incontinent children or adults, which comprises a front
portion, a rear portion, and a crotch portion connecting said front
and rear portions; both said margins of said front portion being
joined to respective side margins of said rear portion so as to
define a waist portion and leg apertures, said undergarment having
a moisture-pervious inner layer adapted to contact the wearer's
skin, an outer layer and an intermediate liquid absorbent panel
disposed therebetween, and an elastic member disposed between the
ends of the inner layer and the outer layer at the rear portion,
said elastic member comprising a plurality of interconnected
longitudinally extending elastic elements defining apertures
therebetween, said elements having different cross-sectional areas
to provide varying degrees of tension across the width of said rear
portion, said inner layer and said outer layer being secured
together through at least some of said apertures.
24. A disposable undergarment as in claim 23 wherein the
longitudinally extending elastic element adjacent the outermost
edge of said rear portion has the greatest degree of tension.
25. A disposable undergarment as in claim 24 wherein the degree of
tension substantially uniformly decreases across the width of the
rear portion containing the elastic member.
26. A disposable undergarment as in claim 23 having an elastic
member disposed between the ends of said inner layer and said outer
layer at the front portion, said elastic member comprising a
plurality of interconnected elastic elements defining apertures
therebetween, said elements having different cross-sectional areas
to provide varying degrees of tension across the width of said
front portion, and said inner layer and said outer layer being
secured together through at least some of said apertures.
27. A disposable undergarment as in claim 23 wherein said
undergarment is also provided with elastic members disposed in the
side margins of said crotch portion, each of said elastic members
comprising a plurality of interconnected elastic elements defining
apertures therebetween, said elements having different
cross-sectional areas to provide varying degrees of tension across
the width of the side margin, and said inner layer and said outer
layer being secured together through at least some of said
apertures.
28. A disposable undergarment as in claim 27 wherein the
longitudinally extending elastic element adjacent the outermost
edge of each side margin has the greatest degree of tension.
29. A disposable undergarment as in claim 27 wherein the degree of
tension substantially uniformly decreases across the width of each
side margin.
Description
BACKGROUND OF THE INVENTION
Recent years have seen an increased demand for inexpensive apparel
and the development of new and inexpensive components of
construction and methods of construction of articles of apparel. In
certain instances, there is a demand for apparel that is very
inexpensive and, indeed, disposable. New elastomeric materials and
methods of incorporating them into portions of a garment have been
developed to meet the desire to fit these types of garments to a
human form. For example, U.S. Pat. No. 3,639,917 discloses the use
of a strip of a heat recoverable elastomeric material to gather the
cuff of a disposable hospital gown.
Disposable diapers have been marketed which include an elastic or
stretch member in the longitudinal side edges of the disposable
diaper to provide elasticity about the leg of the infant when the
diaper is applied. Examples of such stretchable fitted diapers
which have elastic members disposed in the longitudinal side edges
of the diaper are shown in U.S. Pat. Nos. 3,860,003 and 4,050,462.
By being able to elastically contract the longitudinal sides of the
diaper which are the leg and thigh encircling portion of the diaper
once placed on an infant, you can compress the diaper about the leg
of the infant. By virtue of this compressing, you reduce leakage at
the leg of the infant and the tighter you make the fit, the more
you tend to reduce leakage. However, if the fit is too tight, you
will cause irritation on this tender portion of the thigh,
especially when the diaper is wet. There are also a number of
patents which disclose means for making the waist encircling
portion of a disposable diaper elastic for tighter fit of the
diaper about the waist of the wearer, for example, as shown and
described in U.S. Pat. Nos. 3,995,637 and 3,995,640. Disposable
diapers usually comprise a facing and a backing layer which are
substantially co-extensive and a somewhat smaller absorbent core or
panel interposed between the facing and backing layer. The facing
and backing layers are adhered together about their perimeter by
hot melt adhesive or other adhesive material as is well known. In
producing stretch or elastic diapers, an elastic member in its
stretched or partially stretched state, is interposed between the
facing and backing sheets along one or more edges of the diaper.
The elastic member is adhered either to the facing and/or the
backing sheets by adhesive or similar means and allowed to relax to
produce elastic sections at the edges of the diaper. An example of
a method for inserting elastic members in disposable diapers is
disclosed in U.S. Pat. No. 4,081,301.
The incorporation of these elastic members into disposable diapers
has increased both the cost of materials used in the diaper and the
cost of construction of disposable diapers. With solid elastic
members, it is necessary to adhere the side edges of the facing and
backing sheets together, either directly or by their mutual
attachment to the elastic member.
When adhesively securing such an elastic member into a disposable
diaper, the adhesive chosen must be elastomeric or must be applied
in a discontinuous pattern or the glue may make the diaper too
stiff to gather.
In commonly assigned co-pending patent application, Ser. No. 60,704
filed July 25, 1979, there is disclosed apertured elastic members
which have substantial advantages over other types of elastic
members in that they are simpler and more economical to insert and
function very well by providing a good fit with a minimum of
irritation. The present invention is an improvement on such
apertured elastic members.
The laminated structures of the present invention provide improved
fit about the portion of the human body to which they are applied.
In the various parts of the extremities of the human body, such as
the wrist, thigh, etc., the circumference of the extremity
increases as you move along that extremity towards the body torso.
Therefore, an elastic of any width will apply different forces on
that extremity with the most force and the primary seal usually
being at the contact line between the elastic and the body part
having the greatest circumference.
Contrasted to the above, the apertured elastic member used in the
laminated structures of the present invention has a varying degree
of tension across its width and can be used to apply uniform forces
about and along the extremity or even to apply the greatest force
at the contact line between the elastic and the body part having
the least circumference. The laminated structures of the present
invention provide not only an improved fit but unexpectedly improve
sealing capabilities with a minimum of irritation.
SUMMARY OF THE INVENTION
What I have discovered is an improved laminated structure having a
marginal area with a gathered portion which provides improved fit
about a portion of a human body. The laminated structure comprises
first and second substrates of flexible, gatherable material and an
elastic member disposed between the substrates in the marginal area
thereof. The elastic member comprises a plurality of interconnected
longitudinally extending elastic elements. The longitudinal
elements have different cross-sectional areas to provide varying
degrees of tension across the width of the marginal area. The first
and second substrates are secured together through at least some of
the apertures.
The cross-sectional areas may vary quite widely across the width of
the elastic member. However, the degree of taper in most body
extremities is quite gradual and, hence, large variations in the
cross-sectional areas is not required for most end uses.
Theoretically, the elastic force applied is directly proportional
to the cross-sectional area; i.e., as the area is increased, the
force applied will also increase in a proportional relationship. In
practice, this is not exactly the case as the materials to which
the elastic member is laminated do have some effect on the elastic
member and the force to area relationship. In the elastic member of
the present invention, individual longitudinally extending elements
may have a cross-sectional area of from about 0.00001 sq. inches to
about 0.0025 sq. inches and preferably from about 0.00005 to 0.0005
sq. inches.
The laminated structure of the present invention may be used in any
fitted garment but perhaps is most suited for use in inexpensive
and disposable apparel. The laminated structure can be incorporated
into the sleeve cuff, the leg encircling portion, about the neck,
and the waist of an article of apparel. In particular, the
laminated structure may be incorporated into both the waist and
thigh encircling portions of a disposable diaper or other
disposable undergarments. The improved laminated structure of the
present invention reduces the pressure applied to the skin of the
wearer and, in a disposable diaper or a disposable undergarment
reduces the possibility of irritation and rash when wet. The
laminated structure of the present invention may also be used in
such products as elastic bandages, fitted tableclothes, nursing
pads, and the like.
The laminated structures of the present invention may be readily
produced by inserting the described elastic members in a stretched
condition between first and second substrates and these substrates
adhered together between some of the openings in the elastic member
to hold the elastic member in place. If desired, the elastic member
may be held in place over only a portion of its length and may then
be severed in portions not held in place and allowed to relax and
contract in such unheld portion.
The elastic member has a width of from about 1/4 inch to about 2
inches and the member may have a thickness of from 1 to 50 mils and
preferably from about 5 to 20 mils. The elastic member may be made
of any of the standard film materials which are stretchable and are
recoverable and have a modulus of elasticity at 100 percent
elongation of from about 20 to 2000 lbs./sq. inch. In a disposable
diaper in accordance with the present invention, the elastic member
may be disposed between the backing and facing sheet of the diaper
in the longitudinal side margins of the diaper.
It should be pointed out that by using the elastic members in
accordance with the present invention, the insertion of the member
into the product and the adherence thereto is greatly simplified
and, hence, has considerable economic benefit in the manufacturing
process. The apertured portion insures a uniform, intermittent
lamination between the elastic and non elastic layers and reduces
the criticality of adhesive application. Also, the apertures
combined with adhesion of the layers through these apertures
provides that the final lamination acts or performs in its stretch,
recovery and similar elastic properties substantially the same as
the original elastic member, thus allowing for greater certainty in
predicting the quality and functionality of the final product.
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawings:
FIG. 1 is an enlarged perspective view illustrating an elastic
member which may be used in accordance with the present
invention;
FIG. 2 is an enlarged perspective view illustrating another
embodiment of an elastic member which may be used in accordance
with the present invention;
FIG. 3 is a perspective view illustrating a disposable diaper in
accordance with the present invention, with the diaper laid out
flat;
FIG. 4 is an exploded perspective view showing relative positioning
of the diaper elements depicted in FIG. 2;
FIG. 5 is a perspective view of another embodiment of the
disposable diaper embodying the present invention;
FIG. 6 is a plan view of one embodiment of the disposable diaper of
this invention with a portion broken away to show interior
detail;
FIG. 7 is an enlarged cross-sectional view taken along line 7 7 of
FIG. 6;
FIG. 8 is a plan view of another embodiment of the disposable
diaper of this invention with a portion broken away to show
interior detail;
FIG. 9 is a perspective view of a disposable diaper according to
the present invention viewed in the configuration it assumes when
disposed about a wearer;
FIG. 10 is a plan view of a disposable undergarment laid out flat,
in accordance with the present invention with portions folded back
to show interior detail;
FIG. 11 is a perspective view of the disposable undergarment of
FIG. 9 viewed in the configuration it assumes when disposed about a
wearer; and
FIG. 12 is a simplified perspective view of a cuff assembly on a
sleeve according to the present invention viewed in the
configuration it assumes on the wearer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For a laminated structure of the present invention, the elastic
member is a readily stretchable, preferably thermoplastic member
that possesses a certain minimum elastic recovery.
The term "elastic" as used herein, refers to sheets, films,
ribbons, filaments, and the like which have a recovery of at least
90 percent, when elongated to within 10 percent of their field
point and measured in accordance with the following formula:
where;
L.sub.o =original length of sample
L.sub.e =fully extended length
L.sub.t =length of sample measured three seconds after release from
extended length
The thickness of the elastic member may be from about 1 to 50 mils
and is preferably from about 5 to 20 mils. They have a width of
from 1/4 inch to 2 inches and preferably in diaper applications
widths of from 1/2 inch to 1 inch have been found satisfactory. For
ease of stretchability, the moduls of elasticity of the elastic
member at 100 percent elongation should not exceed about 2000
lbs./sq. inch. The modulus of elasticity is preferably
substantially less than 2000 lbs./sq. inch, and most preferably is
about 75 to about 400 lbs./sq. inch.
As shown in FIG. 1, the elastic member 20 useful in accordance with
the present invention comprises a plurality of longitudinally
extending elastic elements 21a, 21b, 21c and 21d. These elements
are transversely connected by elements 22. The transversely
connecting elements 22 may or may not be elastic. However, as will
be hereinafter described, the elastic members are preferably made
from a single component and, hence, the properties of the member
are substantially uniform throughout the member. The openings 23 in
the elastic members may have any shape such as square, oval, round,
rectangular, or the like. Either square or rectangular shaped
openings are preferred with the longitudinal and transverse
elements perpendicular to each other. This configuration virtually
eliminates any "necking down", reduction in the transverse
dimension when the member is stretched longitudinally, and hence,
facilitates insertion of the member with the product and the
adhesion of the layers of the laminate through the openings in the
elastic member. Depending on the modulus of elasticity of the
material used and the thickness and width of the member, the number
of openings in the elastic member may vary from 2 to 100 openings
per linear inch in both the longitudinal and transverse direction
of the member. In addition, the spacing between the elastic
elements may vary from the transverse to the longitudinal
direction.
The cross-sectional areas of the longitudinally extending elements
may be varied across the width of the marginal area so that the
outermost longitudinally extending elastic elements has the largest
cross-sectional area while the innermost longitudinally extending
element has the smallest cross-sectional area. The longitudinally
extending element between the outermost and innermost elements are
substantially uniformly decreased in cross-sectional area from the
outermost element to the innermost element. A structure such as
that described allows for a uniform application of pressure about a
tapered body portion with the longitudinally extending element
having the largest cross-sectional area being positioned so as to
contact the smallest circumference of the tapered body to which the
structure is applied. Such construction also provides for an
excellent seal about the body portion in that the seal is uniform
over the width of the elastic member as compared to prior art seals
where that seal is substantially at a line about the body. In
another embodiment of the laminated structure of the present
invention, the elastic member comprises a plurality of
longitudinally extending elastic elements in the side marginal area
with the longitudinally extending elements in the second portion of
the margin having the largest cross-sectional area while the
longitudinally extending element at the innermost and at the
outermost edges of the margin having smaller cross-sectional areas.
I have found cross-sectional areas in the individual longitudinally
extending elements of from 0.0001 sq. inches to about 0.0025 sq.
inches to be satisfactory; however, my preferred range is from
0.00005 sq. inches to 0.0005 sq. inches. Of course, this will vary
depending on whether the structure is to be used on the wrist or
leg of an adult or on the wrist or leg of an infant.
As shown in FIG. 1, the longitudinally extending elastic elements
21a, b, c, and d have different cross-sectional areas with 21a
having the smallest cross-sectional area, 21b the next smallest,
21c the next smallest, and 21d the largest cross-sectional area.
This varying cross-sectional allows for a varying tension to be
applied by the elastic member when used.
Referring to FIG. 2, there is shown another embodiment of an
elastic member in accordance with the present invention. In this
embodiment, longitudinally extending elastic members 24 and 25 are
transversely connected by elements 26 to define openings 27
therebetween. The outer longitudinally extending elastic elements
24 have smaller cross-sectional areas then the two inner
longitudinally extending elements 25 to provide varying tension
across the width of the elastic member.
It should be pointed out that though I have shown both the
longitudinal and transversely extending elements as circular in
shape, either or both of them may have other cross-sectional shapes
such as oval, elliptical, square, rectangular or other geometric
shapes.
Referring to FIG. 3, a disposable diaper 28 embodying the present
invention has longitudinal side margins 29 and 30. The central
portion of each side margin is gathered to provide improved fit
about the baby's thighs. The elastic member 31 and 32 in each of
the longitudinal side margins is an elastic member according to the
present invention. Individual components of the disposable diaper
of FIG. 3 are illustrated in FIG. 4. The diaper additionally
includes a first layer or backing layer 33 made of a
moisture-impermeable material, a rectangular absorbent batt 34
superimposed over backing layer 33 and secured thereto by a series
of glue lines 35 deposited on the backing layer, and a second layer
or facing layer 36 made of a moisture-permeable web and positioned
in super imposed relationship to the absorbent batt. The absorbent
batt is of smaller area than the backing and when substantially
centered on the backing, is spaced from the longitudinal sides as
well as the transverse ends of the diaper. The absorbent batt is
flanked on its longitudinal sides by elastic members 31 and 32
located generally parallel the longitudinal edges of the batt and
which, in an extended state, are secured between the backing and
the facing by means of the adhesive lines 35a. A moisture-pervious
facing 36 is superimposed over the absorbent batt and secured to
the backing by means of the end and side portions of the glue lines
35. The facing is also secured to the backing between the openings
in the elastic member by adhesive lines 35a. For securing the
diaper about a baby, the diaper is provided with pressure-sensitive
tape tab members 37 and 38.
In the manufacture of the diaper, only the central portions of the
elastic members 31 and 32 act to gather the longitudinal side
margins of the diaper. The end portions of the elastic members
merely "snap back" to a relaxed, unstretched state and do not act
to gather the diaper.
Another method of manufacturing the disposable diaper of the
present invention, when using thermoplastic elastic members, is to
adhere the elastic member between the facing and backing layers
along the entire longitudinal edge of the diaper. Thereafter, the
portions of the elastic member which is desired not act to gather
the diaper are rendered inelastic by applying heat to that portion
of the member and remove its elasticity.
The elastic member of the present invention may be produced by a
variety of methods such as passing an appropriate stretchable and
recoverable film between the nip of a pattern forming roll and a
back-up roll in a procedure analogous to that shown in U.S. Pat.
Nos. 3,881,381 and 3,632,269. When using such a procedure, the
pattern of the forming roll should be altered to provide for the
varying cross-sectional areas of the longitudinally extending
elements.
FIG. 5 shows another disposable diaper 40 similar to that shown in
FIG. 3 with the exception that all four edge portions; that is, the
two longitudinal side margins 41 and 42 and the front 43 and rear
44 end portions are elastic members in accordance with the present
invention inserted between the facing and the backing with the
central portions thereof elastic.
In the embodiment shown in FIG. 6, a disposable diaper 60 is
provided with a substantially rectangular panel 61 sandwiched
between a backing 62 and facing 63 and together with the backing
and facing define side margins 64 and 65. Curvilinear cut-outs are
provided in the respective central side portions of the facing and
backing for further fit enhancement. Pre-stretched elastic members
68 are positioned in the longitudinal side margins and are secured
between the backing and facing along the longitudinal sides of the
absorbent panel. The elastic members have been heated and rendered
inelastic at end positions 69 and 70. Glue lines 71 secure the
facing and absorbent panel to the backing and adhesive tape tabs 72
and 73 provide diaper securement means.
Referring to FIG. 7, which is a cross-sectional view taken along
7-7 of FIG. 6, there is shown the impervious backing member 62 with
the elastic member 68 secured between the backing member and the
facing member 63 by the glue lines.
The longitudinally extending elements 68a, b, and c have varying
cross-sectional areas with elements 68a having the largest
cross-sectional area and element 68c the smallest cross-sectional
area.
In the embodiment shown in FIG. 8, the disposable diaper 80 is
provided with an absorbent batt 81 and also having curvilinear side
cut-outs and sandwiched between facing 82 and backing 83 having
similar cut-outs. Glue lines 84 serve to secure the batt and facing
to the backing. Elastic members 85 are situated in the general
rectilinear diaper side margins. The elastic members are secured
between the facing and backing at the central portion 86 by
adhesive lines 88 which may be applied at the same time as, and may
lie along the same line as certain of the glue lines 84.
Protruding portions 89 and 90 of the absorbent batt overlap into
the four corners of the diaper.
In the manufacture of this diaper, the elastic members are
positioned on top of the protruding portions. The end portions 85a
of the elastic member are heated and rendered inelastic causing the
elastic member to break over the protruding portions as shown.
The varying cross-sectional area elastic members of the present
invention are especially adaptable for use with different shapes of
diapers. For example, the elastic member of the present invention
provides an excellent fit in diapers with facing and backing
members having shallow cut-outs combined with much deeper cut-outs
or shaping of the absorbent panel.
The varying cross-sectional area elastic members of the present
invention are also very suitable for use in the waistband area of
diapers or other waist encircling garments. Garment and diaper
waistbands tend to roll or fold over when the garment is being
worn. My new elastic member disposed in the waistband of a garment
will readily eliminate such rolling or folding over.
The elastic member suitable for use in the diapers contemplated may
be made from films extruded, calendered, or otherwise formed to the
desired thickness and pattern of openings utilizing low stretch
modulus materials made from any rubbery elastic material.
Specifically unvulcanized thermoplastic compositions which are made
of an elastomeric component and an optional compatible modifier
which is a thermoplastic polymer of a relatively low molecular
weight but solid at ambient temperatures have been found to make
suitable elastic members for use in accordance with the present
invention.
Illustrative of the elastomeric components suitable for present
purposes are block copolymers which comprise terminal thermoplastic
polymer blocks and at least some non-terminal or intermediate
elastomeric polymer blocks. Block copolymers of this general type
may be prepared using a step-wise polymerization initiator; e.g. an
organolithium compound. Such block polymerization techniques are
well known in the art.
The elastic component can be linear or radial A.sup.1 -B-A block
copolymers of mixtures thereof with simple A.sup.1 -B block
copolymers wherein A.sup.1 and A.sup.2 can be alike or different
and represent a thermoplastic polymer block, such as poly (vinyl
arene) block, and B represents an elastomeric polymer block such as
a conjugated diene or a lower (i.e., C.sub.1 -C.sub.4) alkene. The
modifier component is a low molecular weight thermoplastic polymer
having an average molecular weight of about 500 to 7,500 and is
present in the composition in an amount of about zero to about 200
parts by weight per 100 parts by weight of the elastomeric
component.
A preferred thermoplastic film composition for the elastic member
comprises an elastomeric component which contains, as a major
constituent thereof, an unvalcanized linear block copolymer of the
general configuration;
wherein A.sup.1, A.sup.2 and B have the same meaning as
hereinabove. In these block copolymers, the A-blocks are derived
from styrene or styrene homologues, and the Bblocks are derived
from conjugated dienes or lower alkenes. The thermoplastic polymer
modifier is compatible with the elastomeric component and
associates principally with the thermoplastic terminal blocks of
the aforesaid unvulcanized block copolymer. The thermoplastic
polymer modifier preferably has an average molecular weight of
about 1000 to about 3000, and is present in the film composition in
an amount of about 80 to 200 parts by weight per 100 parts by
weight of the elastomeric component.
The preferred A.sup.1 -B-A.sup.2 block copolymers have A-blocks
derived; i.e., polymerized or copolymerized, from styrene or
styrene homologues; and B-blocks derived from conjugated dienes,
such as isoprene or butadiene, or from lower alkenes such as
etylene and butylene. Small proportions of other monomers also may
enter into the block copolymers themselves. The individual A-blocks
can have an average molecular weight of at least about 6000,
preferably in the range of about 8000-30,000, and the A-blocks
constitute about 5--50 percent, preferably about 10--30 percent, by
weight of the block copolymer. The average molecular weight of the
B-blocks for linear A.sup.1 -B-A.sup.2 block copolymers preferably
is in the range of about 45,000-180,000 and that of the linear
copolymer, itself, preferably is in the range of about
75,000-200,000. The average molecular weight of the radial A.sup.1
-B-A.sup.2 block copolymers preferably is in the range of about
125,000-400,000. The term "linear block copolymer" (or copolymers)
includes branched A.sup.1 -B-A.sup.2 copolymers as well as
unbranched A.sup.1 -B-A.sup.2 copolymers. The radial A.sup.1
-B-A.sup.2 copolymers useful for manufacture of elastic members for
diapers of this invention are of the type described in United
States Letters Pat. No. 3,281,383 to Zelinski, et al. and conform
to the following general formula: (A-B.sub.n -X), wherein A is a
thermoplastic block polymerized from styrene or styrene homologues,
B is an elastomeric block derived from conjugated dienes or lower
alkenes, as indicated above, X is an organic or inorganic
connecting molecule, with a functionality of about two to four as
described in U.S. Pat. No. 3,281,383, or possibly with a higher
functionality as described in the Article entitled "New Rubber Is
Backed By Stars" appearing on Page 35 of the June 11, 1975, issue
of Chemical Week. As used hereinabove, "n" has a value
corresponding to the functionality of X.
The preferred elastic member is highly thermoplastic and, though
elastomeric, is unlike rubber in that it exhibits a relatively
sharp melting point and is capable of being heat shaped. Also, the
elastic member can form permanent heat seals to substrates such as
non-woven fabrics or the like, at relatively low heat sealing
temperatures, generally not above about 350.degree. F. The member
is very flexible, extensive and soft, and normally exhibits a
Gurley stiffness of about one or less at a film thickness of one
mil.
Elastic members especially suitable for use in disposable diapers
may be made from combinations of thermoplastic rubber and amorphous
polypropylene. The thermoplastic rubbers used in such combinations
are block copolymers having blocks of polybutadiene or
polyisoprene, and blocks of polystyrene. A review article
discussing these materials is "Structure and Properties of Block
Polymers And Multi-phase Polymer Systems: An Overview of Present
Status and Future Potential", by S. L. Aggarwal, Polymer, Vol. 17,
November 1976, Pages 938-956. Two representative types of
thermoplastic rubbers useful in these combinations are the linear
block copolymers (A-B-A) having a mid-block of polybutadiene or
polyisoprene and end-blocks of polystyrene, and the "star" or
"radial" block copolymers having from 4 to 20 "arms" connected to a
common center. Each arm is an A-B block copolymer, the inner
portion being polybutadiene or polyisoprene, with the outer portion
being polystyrene.
The material added or combined with the thermoplastic rubber,
primarily to improve processability, while still retaining the
characteristic rubbery properties of the rubber, is amorphous
polypropylene. Amorphous polypropylene is a known material. It is
essentially atactic polypropylene having an isotactic content of
not more than about 20 weight percent, and preferably not more than
about 10 weight percent.
The amorphous polypropylene is employed in an amount sufficient to
improve the processability of the thermoplastic rubber when
extruding thin films or sheets. The exact minimum amount of
amorphous polypropylene which must be employed varies somewhat from
case to case, but it is usually of the order of about 10 weight
percent, based on weight or rubber plus amorphous polypropylene,
although the proportion may be as low as about 5 weight percent (on
the same basis) in some cases. The upper limit of polypropylene
will also vary from case to case, depending on the nature of the
ingredients and the use intended for the product. At proportions
above about 35 weight percent (on the same basis) a significant
reduction in the characteristic rubbery elastomeric properties of
the product begin to occur. This may be acceptable for some uses,
and not for others. Thus, the upper limit of amorphous
polypropylene would be that point at which the product still
retains significant rubber elastomeric characteristics.
Other conventional materials, employed in the usual amounts, can be
employed in the mixture for their known purposes. Such materials
include pigments, anti blocking agents, stabilizers, anti-oxidants,
ultraviolet stabilizers, bonding aid, and the like.
In some embodiments of the disposable diaper of the present
invention, the elastic member is a member which may be made elastic
by imparting heat or other forms of energy to the member to shrink
the member and provide it with elastic characteristics.
The heat shrinkable reticulated films which may be used as elastic
members in the disposable diapers of the present invention may be
the polyolefin films which have been oriented to a degree and which
will then become elastic when heat shrunk. Usually, a preferred
technique for orienting the polyethylene film to provide the heat
shrunk elastic properties is by irradiation such as suggested in
British Pat. No. 866,820. Also, useful as the heat shrunk elastic
members are the copolymers of ethylene and vinyl acetate, ethylene
and ethyl acrylate, and the like. The forming of such copolymers is
well known and specific methods of forming such materials are
disclosed in U.S. Pat. Nos. 2,200,429 and 2,953,551. After the
copolymer is formed and made into a film, it is given the proper
orientation as described in the previously mentioned British Pat.
No. 866,820.
The elastic member useful in accordance with the present invention
may also be made from other materials; such as, natural rubber, the
synthetic rubbers, and the like.
Broadly, the elastic members may be made from materials having
elongations of from 20 to 1000 percent and preferably from about 50
to 500 percent with recoveries in the range of 20 to 100 percent
and preferably from 70 to 100 percent. The material should have a
force to stretch it 100 percent of from 30 to 2000 grams.
The important factor to remember is that when the material is
placed in the end product, the material be elastic, as previously
defined, so it functions as such an elastic in the final product.
For example, in the diaper leg band area, the member should have 90
percent ot better recovery in very short periods of time and
preferably almost instantaneously the member should also require a
relatively low amount of force to stretch the leg band area back to
its original or non-gathered length. Such force should be less than
200 grams and may be as low as 20 grams.
FIG. 9 illustrates a diaper 94 in accordance with the present
invention in the configuration it takes when placed on the body of
a wearer. The leg encircling portions 95 of the diaper have
differential elasticity with the outer edge 96 of the opening
having a greater elastic force than the inner portion of the
opening. The diaper is secured about the wearer by the tape tabs
97.
FIG. 10 illustrates a disposable undergarment 100 suitable for use
in toilet training infants, or by incontinent children or adults.
The undergarment has a front portion 101, a rear portion 102, and a
crotch portion 103 comprised of an intermediate liquid absorbent
panel 104 disposed between outer layer 105 and a moisture-permeable
inner layer 106. The waistband of the undergarment may be gathered
by an elastic member 107 located between the ends of the inner and
outer layers at the rear portion and optionally between the ends of
the inner and outer layers at the front portion. The longitudinally
extending elements of this elastic member may all have the same
cross-sectional areas. The undergarment is also provided with
elastic members 108 disposed between the inner and outer layers at
the side margins of the crotch region. The longitudinally extending
elements of these elastic members having varying cross sectional
areas with the outermost elements having the largest
cross-sectional area.
FIG. 11 illustrates the disposable undergarment 100 of FIG. 10
about a wearer in use; both side margins 109 and 110 of the front
portion being joined to respective side margins 111 and 112 of the
rear portion to define a waist portion 113 and self-fitting leg
apertures 114.
FIG. 12 illustrates the cuff portion 116 of a garment 117 on the
arm of a wearer. The material at the cuff portion is folded over on
itself and an elastic member 118 in accordance with the present
invention is disposed between the two layers formed by the fold.
The longitudinally extending elements of the elastic member have
varying cross sectional areas with the element 119 closest the hand
having the largest cross sectional area and the element furthest
120 from the hand having the smallest cross-sectional area.
Several different types of materials may be used for disposable
apparel, for example, the material may be a non-woven web made of a
mixture of fibers consisting predominantly of inexpensive, short,
cellulosfc fibers such as short wood pulp fibers or cotton linters
in amounts of 75 percent to 98 percent, the balance being textile
length fibers such as rayon as described in U.S. Pat. No. 3,663,348
to Liloia, et al.
Non-woven materials suitable for use in disposable apparel such as
the forming of dipaers of this invention can have fabric weights in
the range of from about 0.5 to 5 ounces per square yard and
densities of less than 0.15 g/cc., generally in the range of 0.5 to
about 0.1 g/cc. The dry strength of the material for a fabric
having a weight of about 1.5 ounces per square yard is at least
0.15 lbs. per inch of width in the machine direction and at least
0.1 lb. per inch of width in the cross direction. Such fabrics have
good elongation, loft, softness, and drape characteristics.
Materials may also be made of an apertured non woven fabric which
is formed, for example, in accordance with the teachings of
commonly assigned U.S. Pat. Nos. 2,862,251; 3,081,514; and
3,081,515. Furthermore, materials may also be made from other types
of fabric such as those disclosed and described in U.S. Pat. No.
3,485,706 to Evans. Such materials can be made of naturally
occurring fibers, synthetic fibers or blends thereof. Typical
diaper facings made of polyester type fibers may have a weight of
about 0.75 ounces per square yard.
The facing may be the same size as, and coterminous with, the
backing; or alternatively, the facing may be wider than the backing
and have its side edges inwardly folded so that the facing is
coterminous with the backing, as is shown in FIG. 3 of U.S. Pat.
No. 3,612,055. In the latter case, the elastic members may be
secured above the inwardly folded side edges of the facing. In
addition, facings may be made from non apertured materials such as
non-woven isotropic webs or apertured polyolefin or polyester films
having the desired mositure permeability. In all of the
aforementioned facings, the materials should be relatively
hydrophobic so as to retard wicking within the facing.
The moisture absorbent batt or panel of a desired shape, but
smaller than the facing and backing, can be formed in accordance
with the teachings of U.S. Pat. No. 3,612,055 to Mesek, et al.
A suitable backing material for the disposable undergarments
embodying the present invention can be an opaque polyolefin; for
example, polyethylene about 0.001 inch thick. Another suitable
material for this purpose is polyethylene terephthalate having a
thickness of about 0.005 inch.
In use, the disposable diaper is applied to the baby by laying out
the diaper on a single flat surface and placing the baby thereon.
The waist underlying end of the diaper is that end having the
fasterner means and the other end of the diaper extends downwardly
between the baby's legs. Next, the downwardly extending edge of the
diaper is brought up between the baby's legs to a position covering
the perineum and contiguous with the front portion of the baby's
waist. The diaper thereafter is secured to the baby by placing the
corners of the waist portion of the abdomen covering end as far
around the baby's waist as they will go and by bringing the corners
of the underlying end of the diaper into an overlapping
relationship with the aforementioned corners so that the diaper
snugly encircles the baby's waist and provides a custom fit. The
adhesive tape fasteners are then prepared for use and the diaper is
brought in a desired position by simply urging the
pressure-sensitive adhesive surface of the tape tap in contact with
the adjacent outer surfaces of the opposite corner of the
diaper.
In some instances, it may be desirable to have a second fastener
available that can be applied just above the thigh of the infant
and below the standard fastener to improve and secure the fit of
the stretch diaper.
A technique that may be used in the manufacture of the diaper in
accordance with the present invention is to apply the adhesive to
that portion of the backing or facing layer to which the elastic
member is to be secured. In assembling the diaper, pressure is
applied to the diaper in the region of the elastic member to adhere
the facing and backing together between the apertures in the
elastic member.
Broadly, the method of manufacturing the elastic structure of the
present invention comprises feeding the novel elastic member in a
stretched condition between a pair of web surfaces. One of the web
surfaces carries an adhesive. The laminate is pressed together and
the web surfaces secured to each other through the apertures in the
elastic member. The elastic member is then severed and portions
allowed to relax or when a thermoplastic elastic member is used,
portions may be heated and rendered inelastic.
It should be pointed out that the term disposable does not always
mean a single use product. Though such a definition is correct when
referring to diapers, other disposable apparel may be worn a number
of times and even in some instances may withstand hand or even
machine laundering a number of times.
The foregoing description of the drawings are illustrative and are
not to be taken as limiting. Still other variations and
modifications are possible without departing from the spirit and
scope of the present invention.
* * * * *